Hi. I'm assuming that you are referring to speaker outputs on the receiver (if not, let me know).
You can do that, but you need to know some things first. When you connect speakers in parallel like that, you are decreasing the electrical impedance experienced by your receiver. That will result in a larger current draw. If your receiver can handle it, then you will be okay doing it.
The more knowledgeable people here might disagree, and I'll defer to them. If you let us know which receiver you have and which speakers you have, then we could give you a more specific answer for your particular set-up.